His Wednesday column was on the three bombs allegedly hanging over all of our heads, two of them of the metaphorical variety: Debt and climate change. To make his case that climate change is some kind of imminent and deadly threat, Friedman conjured up a wildly implausible scenario out of a dystopian science fiction movie.

Today's youth are growing up in the shadow of three bombs -- any one of which could go off at any time and set in motion a truly nonlinear, radical change in the trajectory of their lives.

The first, of course, is still the nuclear threat, which, for my generation, basically came from just one seemingly rational enemy, the Soviet Union, with which we shared a doctrine of mutual assured destruction. Today, the nuclear threat can be delivered by all kinds of states or terrorists, including suicidal jihadists for whom mutual assured destruction is a delight, not a deterrent.

But there are now two other bombs our children have hanging over them: the debt bomb and the climate bomb.

As we continue to build up carbon in the atmosphere to unprecedented levels, we never know when the next emitted carbon molecule will tip over some ecosystem and trigger a nonlinear climate event -- like melting the Siberian tundra and releasing all of its methane, or drying up the Amazon or melting all the sea ice in the North Pole in summer. And when one ecosystem collapses, it can trigger unpredictable changes in others that could alter our whole world.

Does Friedman know that "The Day After Tomorrow" is, you know, just a movie? In Roland Emmerich's 2004 dystopian thriller, the world plunges into instant climate change when an ice shelf breaks away in Antarctica. But Friedman has gone even further; he's worked out our doomsday down to the molecular level.